Spectroscopic module

ABSTRACT

The spectroscopy module  1  is provided with a body portion  2  for transmitting light L 1 , L 2 , a spectroscopic portion  3  for dispersing light L 1  made incident from the front plane  2   a  of the body portion  2  into the body portion  2  to reflect the light on the front plane  2   a , a light detecting element  4  having a light detecting portion  41  for detecting the light L 2  dispersed and reflected by the spectroscopic portion  3  and electrically connected to a wiring  9  formed on the front plane  2   a  of the body portion  2  by face-down bonding, and an underfill material  12  filled in the body portion  2  side of the light detecting element  4  to transmit the light L 1 , L 2 . The light detecting element  4  is provided with a light-passing hole  42  through which the light L 1  advancing into the spectroscopic portion  3  passes, and a reservoir portion  43  is formed on a rear plane  4   a  of the body portion  2  side in the light detecting element  4  so as to enclose a light outgoing opening  42   b  of the light-passing hole  42.

TECHNICAL FIELD

The present invention relates to a spectroscopy module for dispersinglight to detect the light.

BACKGROUND ART

As conventional spectroscopy modules, there are known, for example,those disclosed in Patent Documents 1 to 3. Patent Document 1 hasdisclosed a spectroscopy module which is provided with alight-transmitting supporting body, an incident slit portion which makeslight incident into the supporting body, a concave diffraction gratingfor dispersing the light made incident into the supporting body toreflect the light, and a diode for defecting the light dispersed andreflected by the concave diffraction grating.

-   Patent Document 1: Japanese Published Unexamined Patent Application    No. H04-294223-   Patent Document 2: Japanese Published Unexamined Patent Application    No. 2004-354176-   Patent Document 3: Japanese Published Unexamined Patent Application    No. 2003-243444

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

Nevertheless, in the spectroscopy module described in Patent document 1,upon attachment of the incident slit portion and the diode to thesupporting body, there is a fear that a relative positional relationshipbetween the incident slit portion and the diode may deviate, thusresulting in a decrease in reliability of the spectroscopy module.

Now, the present invention has been made in view of the above situation,an object of which is to provide a highly reliable spectroscopy module.

Means for Solving the Problems

In order to attain the above object, the spectroscopy module of thepresent invention is provided with a light-transmitting body portion, aspectroscopic portion for dispersing light made incident from apredetermined plane of the body portion into the body portion to reflectthe light on the predetermined plane, a light detecting portion todetect the light dispersed and reflected by the spectroscopic portion,the light detecting element is electrically connected to wiring formedon the predetermined plane of the body portion by face-down bonding, andis provided with a light-transmitting underfill material filled in thebody portion side of the light detecting element, the light detectingelement is provided with a light passing hole through which the lightadvancing into the spectroscopic portion passes, and a reservoir portionis formed so as to enclose a light outgoing opening of the light passinghole on a plane of the body portion side of the light detecting element.

In the spectroscopy module, a light passing hole through which lightadvancing to the spectroscopic portion passes and a light detectingportion for detecting light dispersed and reflected by the spectroscopicportion are formed at the light detecting element. Therefore, it ispossible to prevent the deviation of relative positional relationshipbetween the light passing hole and the light detecting portion. Further,the light detecting element is electrically connected to wiring formedon the predetermined plane of the body portion by face-down bonding, anda light-transmitting underfill material is filled in the body portionside of the light detecting element. Therefore, the body portion and thelight detecting element can be improved in mechanical strength and lightwhich advances between the body portion and the light detecting elementcan also be adjusted for the refraction index. In this instance, wherethe underfill material filled between the light detecting element andthe body portion advances into a light passing hole of the lightdetecting element, there is a case that light made incident into thelight passing hole may be deflected or diffused, depending on the shapeof the surface on the light incident side of the underfill materialinside the light passing hole. In the present invention, a reservoirportion is formed so as to enclose a light outgoing opening of the lightpassing hole on a plane of the body portion side of the light detectingelement. Thereby, the underfill material is reserved at the reservoirportion to prevent the underfill material from entering into the lightpassing hole. Therefore, light is not deflected or diffused by theunderfill material but can be made incident into the body portion. Thus,according to the spectroscopy module, it is possible to improve thereliability.

In the spectroscopy module of the present invention, it is preferablethat the wiring has a light absorbing layer on a predetermined plane.For example, where the wiring is directly formed on the predeterminedplane of the body portion in order to attach the wiring to the bodyportion more firmly, thereby preventing the wiring from breaking or thelike, the light absorbing layer can be used to prevent stray light frombeing reflected in a diffused manner due to the wiring.

In the spectroscopy module of the present invention, it is preferablethat there is formed on a predetermined plane a light absorbing layerhaving a first light passing portion through which light advancing tothe spectroscopic portion passes and a second light passing portionthrough which light advancing to the light detecting portion passes. Inthis instance, the light absorbing layer acts to suppress the generationof stray light and also absorb the stray light, thus making it possibleto suppress the stray light from being made incident into the lightdetecting portion of the light detecting element.

The reservoir portion may be an annular groove formed so as to enclose alight outgoing opening and may be a recessed portion formed so as toinclude the light outgoing opening. In these instances, it is possibleto form the reservoir portion in a simple structure.

It is preferable that the groove is formed so as to enclose the firstlight passing portion when viewed from the center line of the lightpassing hole. It is also preferable that the recessed portion is formedso as to include the first light passing portion when viewed from thecenter line of the light passing hole. In these instances, an underfillmaterial is reserved on the groove or at the recessed portion to preventthe underfill material from entering into the first light passingportion of the light absorbing layer. Therefore, light is not deflectedor diffused by the underfill material and the light can be made incidentinto the body portion.

Effect of the Invention

According to the present invention, it is possible to improve thereliability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a spectroscopy module of a first embodiment ofthe present invention.

FIG. 2 is a cross sectional view of the spectroscopy module taken alongline II to II given in FIG. 1.

FIG. 3 is a perspective view showing the vicinity of a light passinghole of the light detecting element of the spectroscopy module 1 givenin FIG. 1, when viewed from the body portion.

FIG. 4 is an enlarged cross sectional view showing the vicinity of alight passing hole of the spectroscopy module in FIG. 1.

FIG. 5 is a perspective view showing the vicinity of a light passinghole of the light detecting element of a spectroscopy module of a secondembodiment, when viewed from the body portion.

FIG. 6 is an enlarged cross sectional view showing the vicinity of alight passing hole of the spectroscopy module of the second embodiment.

EXPLANATION OF REFERENCE NUMERALS

1: spectroscopy module

-   2: body portion-   2 a: front plane (predetermined plane)-   3: spectroscopic portion-   4: light detecting element-   4 a: rear plane (plane on the body portion side)-   6: light absorbing layer-   6 a: light passing portion (first light passing portion)-   6 b: light passing portion (second light passing portion)-   9: wiring-   9 d: light absorbing layer-   12: underfill material-   16: light transmitting plate-   41: light detecting portion-   42: light passing hole-   42 b: light outgoing opening-   43: reservoir portion-   44: groove-   45: recessed portion-   CL: center line

BEST MODES FOR CARRYING OUT THE INVENTION

Hereinafter, a detailed description will be given for preferredembodiments of the present invention by referring to the drawings. It isnoted that in the individual drawings, the same reference letters ornumerals are given to the same and corresponding parts, with overlappingdescription omitted.

First Embodiment

FIG. 1 is a plan view of a spectroscopy module of a first embodiment ofthe present invention. FIG. 2 is a cross sectional view of thespectroscopy module taken along line II to II given in FIG. 1. As shownin FIG. 1 and FIG. 2, the spectroscopy module 1 is provided with alight-transmitting body portion 2, a spectroscopic portion 3 fordispersing light L1 made incident from a front plane (predeterminedplane) 2 a of the body portion 2 into the body portion 2 to reflect thelight on the front plane 2 a, and light detecting element 4 fordetecting light L2 dispersed and reflected by the spectroscopic portion3. The spectroscopy module 1 is to disperse the light L1 into aplurality of lights L2 by the spectroscopic portion 3 and detect thelights L2 by the light detecting element 4, thereby measuring thewavelength distribution of the light L1 and the intensity of a specificwavelength component or the like.

The body portion 2 is provided with a light-transmitting member 2 ₁formed in a rectangular plate shape by using a light-transmitting glassor a light-transmitting resin such as BK7, Pyrex (registered trade mark)or quartz and a light-transmitting member 2 ₂ formed at a predeterminedposition on the rear plane of the light-transmitting member 2 ₁. Thelight-transmitting member 2 ₂ is formed by using the same material asthat of the light-transmitting member 2 ₁, that is, a light-transmittingorganic-inorganic hybrid material or a light-transmitting low-meltingtemperature glass for replica molding in a predetermined shape (in thisinstance, a shape in which a hemisphere lens is cut out by two planesapproximately orthogonal to the flat plane portion thereof and alsoapproximately parallel to each other to give the side planes), therebyacting as a lens for forming an image on a light detecting portion 41 ofthe light detecting element 4 on the basis of light L2 dispersed andreflected by the spectroscopic portion 3. The light-transmitting member2 ₂ is arranged so that the side planes are approximately parallel withthe longitudinal direction of the light-transmitting member 2 ₁ andbonded to the light-transmitting member 2 ₁ with an optical resin or bydirect bonding, where it is made with the same material as that of thelight-transmitting member 2 ₁.

The spectroscopic portion 3 is a reflection type grating having adiffracting layer 14 formed on the outer surface of thelight-transmitting member 2 ₂ and a reflecting layer 5 formed on theouter surface of the diffracting layer 14. The diffracting layer 14 is aserrated cross-sectional blazed grating, a rectangular cross-sectionalbinary grating, a sinusoidal cross-sectional holographic grating or thelike. The diffracting layer 14 is formed, for example, by coating aphotosensitive resin on the outer surface of the light-transmittingmember 2 ₂ and then using a light-transmitting mold (grating mold) madeof quartz or the like to subject the photosensitive resin to UV curing.The diffracting layer 14 is made more stable when heated and cured afterthe UV curing. The reflecting layer 5 is formed in a film shape, forexample, by evaporating Al, Au or the like on the outer surface of thediffracting layer 14. Further, a protective layer made with SiO₂, MgF₂or the like may be formed on the reflecting layer 5. It is noted thatmaterials of the diffracting layer 14 shall not be limited tophotosensitive resins but may include photosensitive glass,photosensitive organic-inorganic hybrid materials, heat-deformableresins/glass and organic-inorganic hybrid materials, etc.

The light detecting element 4 is provided with a light detecting portion41 in which long photodiodes are arrayed one-dimensionally in adirection approximately orthogonal to the longitudinal direction thereofto detect light L2 dispersed and reflected by the spectroscopic portion3 and a light passing hole 42 which is installed together with the lightdetecting portion 41 in a direction at which the photodiodes arearranged one dimensionally and through which light L1 advancing to thespectroscopic portion 3 passes. The light passing hole 42 is a slitextending in a direction approximately orthogonal to the longitudinaldirection of the light-transmitting member 2 ₁ and formed by etching,blasting or laser processing etc., in a state that it is positioned at ahigh accuracy with respect to the light detecting portion 41. The lightdetecting element 4 is arranged in such a manner that a direction atwhich the photodiodes are arrayed one dimensionally is approximately inagreement with the longitudinal direction of the light-transmittingmember 2 ₁ and also the light detecting portion 41 turns to the frontplane 2 a of the body portion 2. It is noted that the light detectingelement 4 shall not be limited to the photodiode array but may include aC-MOS image sensor, a CCD image sensor or the like.

On the front plane 2 a (more specifically, the front plane of thelight-transmitting member 2 ₁) of the body portion 2, there is formed awiring 9 made of a single film of Al, Au or the like or a laminated filmof Ti—Pt—Au, Ti—Ni—Au, Cr—Au or the like. The wiring 9 is provided witha plurality of pad portions 9 a arranged at the center of thelight-transmitting member 2 ₁, a plurality of pad portions 9 b arrangedat the end of the light-transmitting member 2 ₁ in the longitudinaldirection and a plurality of connection portions 9 c for connecting thecorresponding pad portions 9 a and the pad portions 9 b. Further, thewiring 9 is provided on the front plane 2 a of the body portion 2 with alight absorbing layer 9 d made of a single film of CrO or the like or alaminated film of Cr—CrO or the like.

Further, on the front plane 2 a of the body portion 2, there is formed alight absorbing layer 6 so as to expose the pad portions 9 a, 9 b of thewiring 9 and also cover the connection portions 9 c of the wiring 9.

The light absorbing layer 6 is provided with a light passing portion(first light passing portion) 6 a through which light L1 advancing tothe spectroscopic portion 3 passes and a light passing portion (secondlight passing portion) 6 b through which light L2 advancing to the lightdetecting portion 41 of the light detecting element 4 passes. The lightpassing portion 6 a is a slit extending in a direction approximatelyorthogonal to the longitudinal direction of the light-transmittingmember 2 ₁. The light absorbing layer 6 is subjected to apredetermined-shaped patterning and formed integrally by using CrO, aCrO-containing laminated film, black resist or the like.

An external terminal of the light detecting element 4 is electricallyconnected to the pad portion 9 a exposed from the light absorbing layer6 by face-down bonding via a bump 15 so that the light passing hole 42opposes the light passing portion 6 a of the light absorbing layer 6 andthe light detecting portion 41 also opposes the light passing portion 6b of the light absorbing layer 6. Further, a flexible printed board 11for taking out an output signal of the light detecting element 4 iselectrically connected by wire bonding to the pad portions 9 b exposedfrom the light absorbing layer 6. Then, an underfill material 12 fortransmitting at least light L2 is filled in the body portion 2 side (inthis instance, between the light detecting element 4 and thelight-transmitting member 2 ₁ or the light absorbing layer 6) of thelight detecting element 4.

FIG. 3 is a perspective view showing the vicinity of the light passinghole of the light detecting element of the spectroscopy module given inFIG. 1, when viewed from the body portion side. FIG. 4 is an enlargedcross sectional view showing the vicinity of the light passing hole ofthe spectroscopy module given in FIG. 1. As shown in FIG. 3 and FIG. 4,the light passing hole 42 is provided with a light incident-side portion42 ₁ for demarcating a light incident opening 42 a from which light L1is made incident and a light outgoing-side portion 42 ₂ for demarcatinga light outgoing opening 42 b from which light L1 is made outgoing. Thelight outgoing-side portion 42 ₂ is formed in a rectangular solid shapeextending in a direction approximately orthogonal to the longitudinaldirection of a light-transmitting member 2 ₁ and the light incident-sideportion 42 ₁ is formed in a square pyramid shape widening from the lightoutgoing-side portion 42 ₂ to the opposite direction. More specifically,the light passing hole 42 is formed in such a manner that the lightincident opening 42 a includes the light outgoing opening 42 b, whenviewed from the center line (CL) thereof.

A reservoir portion 43 is formed on a rear plane 4 a of the body portion2 side of the light detecting element 4 so as to enclose the lightoutgoing opening 42 b. The reservoir portion 43 is constituted with arectangular annular groove 44 formed so as to enclose the light outgoingopening 42 b. A region enclosed by the groove 44, when viewed from thecenter line (CL) of the light passing hole 42, is greater in area thanthe light passing portion 6 a of the light absorbing layer 6.

In the above-constituted spectroscopy module 1, light L1 is madeincident from the front plane 2 a of the body portion 2 into the bodyportion 2 via the light passing hole 42 of the light detecting element 4and the light passing portion 6 a of the light absorbing layer 6,advancing inside the light-transmitting members 2 ₁, 2 ₂ and arriving atthe spectroscopic portion 3. The light L1 which has arrived at thespectroscopic portion 3 is dispersed into a plurality of lights L2 bythe spectroscopic portion 3. The thus dispersed light L2 is reflected bythe spectroscopic portion 3 on the front plane 2 a side of the bodyportion 2, advancing inside the light-transmitting members 2 ₂, 2 ₁,arriving at the light detecting portion 41 of the light detectingelement 4 via the light passing portion 6 b of the light absorbing layer6. The light L2 which has arrived at the light detecting portion 41 isdetected by the light detecting element 4.

As so far described, in the spectroscopy module 1, the light passinghole 42 through which light L1 advancing to the spectroscopic portion 3passes and the light detecting portion 41 for detecting light L2dispersed and reflected by the spectroscopic portion 3 are formed at thelight detecting element 4 in a state that they are positioned from eachother at a high accuracy. It becomes unnecessary to install differentmembers for forming the light passing hole 42 and to position betweenthe light passing hole 42 and the light detecting portion 41 (morespecifically, only the spectroscopic portion 3 is positioned withrespect to the light detecting element 4). Therefore, it is possible todownsize the spectroscopy module 1 at a reduced cost.

Further, in the spectroscopy module 1, the light detecting element 4 iselectrically connected to the wiring 9 formed on the front plane 2 aside of the body portion 2 by face-down bonding, and an underfillmaterial 12 for transmitting light L1, L2 is filled in the body portion2 side of the light detecting element 4. As described so far, such aconstitution is provided that the light detecting element 4 iselectrically connected externally via the wiring 9 formed at the bodyportion 2. Thereby, for example, in a case where the flexible printedboard 11 is directly connected to the light detecting element 4(mechanically), a force applied to the flexible printed board 11 at thepoint of using the spectroscopy module 1 is not directly transferred tothe light detecting element 4, thus making it possible to prevent thelight detecting element 4 from receiving loads such as stress and alsodownsizing the light detecting element 4. Further, the underfillmaterial 12 is filled in the body portion 2 side of the light detectingelement 4, by which the body portion 2 and the light detecting element 4can be improved in mechanical strength. It is also possible to adjustthe refraction index on all channels through which light L1, L2advancing between the body portion 2 and the light detecting element 4pass.

Further, in the spectroscopy module 1, a groove 44 (reservoir portion43) is formed on a plane 4 a of the light detecting element 4 so as toenclose the light outgoing opening 42 b of the light passing hole 42.Thereby, the underfill material 12 is reserved at the groove 44(reservoir portion 43), or the underfill material 12 is reserved andalso prevented from entering into the light passing hole 42. Thus, lightcan be made incident into the body portion 2, without being deflected ordiffused by the underfill material 12.

Further, in the spectroscopy module 1, the wiring 9 is provided with alight absorbing layer 9 d on the front plane 2 a side of the bodyportion 2. Thereby, the wiring 9 is attached to the body portion 2 morefirmly to prevent the wiring 9 from breaking or the like. Thus, even ifthe wiring 9 is formed directly on the front plane 2 a of the bodyportion 2, the light absorbing layer 9 d can be used to prevent straylight from being reflected in a diffused manner due to the wiring 9.

Further, in the spectroscopy module 1, there is formed on the frontplane 2 a of the body portion 2 a light absorbing layer 6 having a lightpassing portion 6 a through which light L1 advancing to thespectroscopic portion 3 passes and a light passing portion 6 b throughwhich light L2 advancing to the light detecting portion 41 of the lightdetecting element 4 passes. The light absorbing layer 6 is used tosuppress the generation of stray light and also absorb the stray light,thus making it possible to suppress the stray light from being madeincident into the light detecting portion 41.

Still further, since the reservoir portion 43 is a groove 44 formed soas to enclose the light outgoing opening 42 b, it is possible to formthe reservoir portion 43 in a simple structure.

In addition, in the spectroscopy module 1, the groove 44 is formed so asto enclose the light passing portion 6 a, when viewed from the centerline (CL) of the light passing hole 42. Thereby, the underfill material12 is reserved at the groove 44, or the underfill material 12 isreserved and also prevented from entering into the light passing portion6 a of the light absorbing layer 6. Thus, light can be made incidentinto the body portion 2, without being deflected or diffused by theunderfill material 12.

Second Embodiment

A spectroscopy module 1 of a second embodiment is different from thespectroscopy module 1 of the first embodiment in the constitution of thereservoir portion 43 provided on the plane 4 a side of the lightdetecting element 4.

FIG. 5 is a perspective view showing the vicinity of a light passinghole of the light detecting element of the spectroscopy module in thesecond embodiment when viewed from the body portion. FIG. 6 is anenlarged cross sectional view showing the vicinity of a light passinghole of the spectroscopy module in the second embodiment. In the lightdetecting element 4 of the spectroscopy module 1 of the secondembodiment, as shown in FIG. 5 and FIG. 6, a reservoir portion 43 formedon the plane 4 a of the light detecting element 4 is constituted with arectangular recessed portion 45 formed so as to extend in a directionapproximately orthogonal to the longitudinal direction of thelight-transmitting member 2 ₁ to include the light outgoing opening 42b. A part enclosed by the recessed portion 45 when viewed from thecenter line (CL) of the light passing hole 42 is greater in area thanthe light passing portion 6 a.

As described so far, in the spectroscopy module 1, the recessed portion45 is formed as the reservoir portion 43 on the plane 4 a of the lightdetecting element 4 so as to include the light outgoing opening 42 b ofthe light passing hole 42. Thereby, it is possible to form the reservoirportion 43 in a simple structure.

Further, in the spectroscopy module 1, the recessed portion 45 is formedso as to include the light passing portion 6 a when viewed from thecenter line (CL) of the light passing hole 42. Thereby, an underfillmaterial 12 is reserved at the recessed portion 45, or the underfillmaterial 12 is reserved and also prevented from entering into the lightpassing portion 6 a of the light absorbing layer 6. Thus, light can bemade incident into the body portion 2, without being deflected ordiffused by the underfill material 12.

The present invention shall not be limited to the above-describedembodiments.

For example, the light absorbing layer 6 may be formed on the frontplane 2 a of the body portion 2, and the wiring 9 may be formed on thefront plane of the light absorbing layer 6. In this instance, even ifthe wiring 9 is not provided on the light absorbing layer 9 d, it ispossible to prevent stray light from being reflected in a diffusedmanner due to the wiring 9.

The light-transmitting member 2 ₂, which acts as a lens, may be formedintegrally with the diffracting layer 14 by using light-transmittinglow-melting temperature glass for replica molding or the like. In thisinstance, it is possible to simplify the production process and alsoprevent the deviation of relative positional relationship between thelight-transmitting member 2 ₂ and the diffracting layer 14.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to improve thereliability.

1. A spectroscopy module comprising: a light-transmitting body portion;a spectroscopic portion for dispersing light made incident from apredetermined plane of the body portion into the body portion to reflectthe light on the predetermined plane; a light detecting element having alight detecting portion for detecting the light dispersed and reflectedby the spectroscopic portion and electrically connected to wiring formedon the predetermined plane by face-down bonding; and an underfillmaterial filled in the body portion side of the light detecting elementand capable of transmitting the light; wherein the light detectingelement is provided with a light passing hole through which the lightadvancing into the spectroscopic portion passes, and a reservoir portionis formed so as to enclose a light outgoing opening of the light passinghole on a plane of the body portion side of the light detecting element.2. The spectroscopy module as set forth in claim 1, wherein the wiringis provided on the predetermined plane with a light absorbing layer. 3.The spectroscopy module as set forth in claim 1, wherein a lightabsorbing layer having a first light passing portion through which thelight advancing into the spectroscopic portion passes and a second lightpassing portion through which the light advancing into the lightdetecting portion passes is formed on the predetermined plane.
 4. Thespectroscopy module as set forth in claim 1, wherein the reservoirportion is an annular groove formed so as to enclose the light outgoingopening.
 5. The spectroscopy module as set forth in claim 4, wherein thegroove is formed so as to enclose the first light passing portion whenviewed from the center line of the light passing hole.
 6. Thespectroscopy module as set forth in claim 1, wherein the reservoirportion is a recessed portion formed so as to include the light outgoingopening.
 7. The spectroscopy module as set forth in claim 6, wherein therecessed portion is formed so as to include the first light passingportion when viewed from the center line of the light passing hole.